Ok brakes were great. Sensitive and reactive. Last weekend we went 5mph on a bumpy road. Parked. Hiked and returned 3 hours later. Right away I noticed I had no brakes. Pedal goes to floor and right then it tries to grab. Even at 5-8mph it rolled few feet. No lights. No abs ect.
Hit pavement and instantly returned. Next day I was on road again and did it again and returned to normal. 80mph home and all is well.
Today another road did it. Removed abs fuse and still there. Few minutes it went away. And 120 miles since was great.
What the heck…i could start replacing things but what would cause it over and over going walking speed to make it loose pressure. It never gets hard. No leaks. Just travels further…and bottoms out
This is familiar to me. Check the wheel bearings, especially the front. When the bearings get worn but before they start making noise they can get loose. When the car is driven on a washboard road, the wobble in the bearings can allow the brake rotors to knock the brake pistons back in their bores. With the pistons pushed back, the next time you apply the brakes, the brake pedal travel is much longer. It feels like you don’t have any brakes. If you pump the pedal a couple of times it comes back. That seems like it fits your description of events.
I had a similar experience, where I installed caliper hardware improperly and it was pushing the pads outward too strong, car had a long pedal press to “pump” it after driving with no brakes usage for few miles, then brakes would work again very nicely. Upon proper reassembly, the problem went away.
I found this from racing cars. The bearing stresses are quite high when the car is loaded up in a corner. Even the slightest bit of slop (even within factory tolerance) causes piston knock-back in the calipers and a long pedal. If you expect it, it isn’t so bad. At least the brakes still work, you just need a longer stroke.
Running down a straightaway, you can pump up the brakes with a light tap-tap-tap on the pedal so the pedal is high when you go deep into the brakes. You used to be able to watch this on NASCAR “foot cams” they would show on road courses. I haven’t seen it lately.
Wow guys you might be on to something. I will jack her up later and see if I can feel some wobble.
Only thing that comes up is…why it takes many brake pumps to build pressure…i’d think if the rotor tilted, I would only be making up a pump or two…unless the road continues to throw off the pistons…
Funny too…if it wasn’t for my brake issue, the only other current issue is a weird mild rumble. All suspension parts are good and tires are OKAY. thought maybe uneven wear causing a rumble but they are not that bad…maybe its all pointing to a bad Bearing. I even felt some sway recently too…